docs(reference): Fix PkgIdSpec kind docs (#15049)

Fixes #15048

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Author: weihanglo

src/doc/src/reference/pkgid-spec.md

@@ -27,8 +27,8 @@ query = ( "branch" | "tag" | "rev" ) "=" ref
 pkgname := name [ ("@" | ":" ) semver ]
 semver := digits [ "." digits [ "." digits [ "-" prerelease ] [ "+" build ]]]
 
-kind = "registry" | "git" | "file"
-proto := "http" | "git" | ...
+kind = "registry" | "git" | "path"
+proto := "http" | "git" | "file" | ...
 ```
 
 Here, brackets indicate that the contents are optional.